Density Calculator
Why a Kilogram of Feathers Takes Up More Room Than a Kilogram of Lead
Density is the property that answers a question mass alone can't: how tightly is that mass packed into space? Two objects can weigh the same and still behave completely differently in air, water, or a mixture, purely because of how their mass is distributed through volume. This calculator solves the density relationship in whichever direction you need — density, mass, or volume.
The Formula
ρ = m / V
Rearranged for the other two unknowns:
Volume = Mass / Density
Results come out in kg/m³ when mass is in kilograms and volume is in cubic meters — a unit this calculator also converts to the more familiar g/cm³ for reference.
Where Density Drives Decisions
- Material selection — engineers choose metals, plastics, and composites partly by density when weight is a design constraint, such as in aerospace or automotive parts.
- Buoyancy and flotation — whether an object sinks or floats in a given fluid comes down to comparing its density to the fluid's.
- Fluid identification — measuring density is a quick way to check the concentration or purity of a liquid, from battery acid to antifreeze.
- Geology and mining — density contrasts between rock types are used to infer subsurface composition and locate ore bodies.
Density of Common Materials
| Substance | Density |
|---|---|
| Air (sea level, 15°C) | 1.225 kg/m³ |
| Water (fresh, 4°C) | 1,000 kg/m³ |
| Aluminum | 2,700 kg/m³ |
| Steel | ~7,850 kg/m³ |
| Gold | 19,300 kg/m³ |
Standard reference values for pure substances near room temperature and atmospheric pressure; actual material density can vary with alloy composition, temperature, and pressure.
How to Use This Calculator
- Choose what to solve for: Find Density, Find Mass, or Find Volume.
- For Find Density, enter Mass (kg) and Volume (m³).
- For Find Mass, enter Density (kg/m³) and Volume (m³).
- For Find Volume, enter Mass (kg) and Density (kg/m³).
- Select Calculate to see the result along with the worked formula.
Related Calculations
Once you know an object's mass, see how much force gravity exerts on it with the Force Calculator, or work out hydrostatic pressure at depth in a fluid of known density with the Pressure Calculator.